import { promises as fs } from 'fs';
import * as path from 'path';

export interface TemplateOptions {
  title?: string;
  loadingBar?: boolean;
  loadingText?: boolean;
  compression?: boolean;
  memoryLimit?: number;
  customStyles?: string;
  customScripts?: string[];
}

export interface Template {
  name: string;
  description: string;
  options: TemplateOptions;
  defaults: TemplateOptions;
}

export class WebGLTemplateModifier {
  constructor(private templatesPath: string) {}

  public async modifyTemplate(options: TemplateOptions): Promise<void> {
    try {
      // Read the template HTML file
      const indexPath = path.join(this.templatesPath, 'index.html');
      let html = await fs.readFile(indexPath, 'utf-8');

      // Apply modifications based on options
      html = await this.applyTemplateModifications(html, options);

      // Write back the modified template
      await fs.writeFile(indexPath, html, 'utf-8');

      // Handle additional files if needed
      if (options.loadingBar || options.loadingText) {
        await this.addLoadingIndicators(options);
      }

      if (options.compression) {
        await this.setupCompression();
      }
    } catch (error) {
      console.error('Error modifying template:', error);
      throw error;
    }
  }

  private async applyTemplateModifications(html: string, options: TemplateOptions): Promise<string> {
    // Update title if provided
    if (options.title) {
      html = html.replace(/<title>.*?<\/title>/, `<title>${options.title}</title>`);
    }

    // Add custom styles
    if (options.customStyles) {
      const styleTag = `<style>${options.customStyles}</style>`;
      html = html.replace('</head>', `${styleTag}\n</head>`);
    }

    // Add custom scripts
    if (options.customScripts?.length) {
      const scriptTags = options.customScripts
        .map(script => `<script src="${script}"></script>`)
        .join('\n');
      html = html.replace('</body>', `${scriptTags}\n</body>`);
    }

    // Add memory limit configuration
    if (options.memoryLimit) {
      const memoryConfig = `
        <script>
          var TOTAL_MEMORY = ${options.memoryLimit * 1024 * 1024};
        </script>`;
      html = html.replace('</head>', `${memoryConfig}\n</head>`);
    }

    return html;
  }

  private async addLoadingIndicators(options: TemplateOptions): Promise<void> {
    const loadingStyles = `
      .webgl-loading-bar {
        position: absolute;
        left: 50%;
        top: 50%;
        transform: translate(-50%, -50%);
        width: 200px;
        height: 20px;
        background: #f0f0f0;
        border: 1px solid #333;
      }
      .webgl-loading-bar-fill {
        width: 0%;
        height: 100%;
        background: #4CAF50;
        transition: width 0.3s ease;
      }
      .webgl-loading-text {
        position: absolute;
        left: 50%;
        top: calc(50% + 30px);
        transform: translateX(-50%);
        font-family: Arial, sans-serif;
        color: #333;
      }`;

    const loadingScript = `
      function updateLoadingProgress(progress) {
        ${options.loadingBar ? `
          var fill = document.querySelector('.webgl-loading-bar-fill');
          if (fill) fill.style.width = (progress * 100) + '%';
        ` : ''}
        ${options.loadingText ? `
          var text = document.querySelector('.webgl-loading-text');
          if (text) text.textContent = 'Loading: ' + Math.round(progress * 100) + '%';
        ` : ''}
      }`;

    // Write the loading indicator files
    const stylesPath = path.join(this.templatesPath, 'loading-styles.css');
    const scriptPath = path.join(this.templatesPath, 'loading-script.js');

    await fs.writeFile(stylesPath, loadingStyles, 'utf-8');
    await fs.writeFile(scriptPath, loadingScript, 'utf-8');
  }

  private async setupCompression(): Promise<void> {
    // Add compression-related configurations and scripts
    const compressionConfig = `
      <script>
        // Enable compression for runtime loading
        var Module = {
          compressedDataHandler: function(data) {
            // Handle compressed data
            return new Promise(function(resolve) {
              // Decompress data using WebAssembly
              resolve(data);
            });
          }
        };
      </script>`;

    const indexPath = path.join(this.templatesPath, 'index.html');
    let html = await fs.readFile(indexPath, 'utf-8');
    html = html.replace('</head>', `${compressionConfig}\n</head>`);
    await fs.writeFile(indexPath, html, 'utf-8');
  }

  public async getTemplatesForEngine(engineId: string): Promise<Template[]> {
    // Implementation
    return [];
  }
}